Electric switch



W. G. HARLOW ELECTRIC SWITCH Nov. 8; 1949 Fil ed Oct. 29, 1945 A #9 i mim t d H i s Atorney.

Patented Nov. 8, 1949 2,487,545 ELECTRIC SWITCH Winton G. Harlow, Upper Darby, Pa., assignor to General Electric Company, a corporation of New York Application October 29, 1945, Serial No. 625,272

2 Claims. (Cl. 200-162) My invention relates to improvements in electric switches and more particularly manually operable knife switches and especially fused knife switches.

Knife switches have, heretofore, involved the use of too much material, too much space on the panel or switch board as well as conducting and manual operating elements of involved construction or too many parts to provide a switch satisfactory from the standpoint of manufacture, reliability, flexibility of application and economy. Accordingly, an object of my invention is to provide an improved knife switch structure which is simple and economical to manufacture from relatively few parts and which is compact and readily adaptable for closely spaced fused switch panel mountings. Another object of my invention is to provide an improved finger-operated knife switch having a sturdy insulating fingeroperable block handle close-coupled with relatively lightweight switch conducting parts conducting relatively high currents without serious heating. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide a knife switch structure wherein a relatively light U-shaped blade member having a rectangular bight formed from a flat electric current conductor, is readily and rigidly secured to .an insulating finger-operable channel block handle provided with a lengthwise extending rectangular mounting groove for registering nested en- .gagement with the rectangular bight of the blade member so as to prevent movement thereof relatively to the handle and also to insure parallel alignment of the blade members in a multipole switch. Also in accordance with my invention, I provide a first round switch pivot stud terminating in a fiat contact portion, a second round switch contact stud terminating in a cylindrical contact portion and having a motion limiting shoulder below the contact portion, and cooperating with these two studs, a U-shaped blade member for spanning the flat and the cylindrical contact portions and whose legs adjacent the rectangular bight are spaced apart sufficiently less than the diameter of the cylindrical contact portion of the second stud to insure relatively high contact pressure when the blade member and the second stud are in cooperative engagement. Further in accordance with my invention, the ends of the legs of the U- shaped blade member are inwardly offset to a spacing substantially equal to the thickness of the flattened portion of the first stud to which the legs are pivotally clamped.

My invention will be better understood from the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying drawing. Fig. 1 is a side elevation, partly in section, of a double-pole fused finger-operable knife switch embodyin my invention; Fig. 2 is a front elevation of the embodiment of my invention shown in Fig. 1; Fig. 3 is a sectional elevation on the line 3-3' of Fig. 1 showing the detailed construction of 5 the combined switch pivot and fuse mounting stud but to a larger scale; Fig. 4 is a sectional elevation on the line 4-4 of Fig. 2 showing the insulating finger-operable block handle close coupled mounting on the rectangular bight of the switch blade'but to a larger scale; and Fig. 5

illustrates a. modification of a part of my invention.

For the purpose of illustrating my invention, I have shown in Figs. 1 and 2 a two-pole knife 5 switch comprising a first row of round hinge studs l0, each terminating in a relatively thin flat portion ll normal to the row, an opposite.

row of round contact studs l3 each terminating in a rounded contact portion it having its axis 0 in opposing alignment with the flat portion H of the corresponding stud Ill in the first row and provided with a movable contact motion-' limiting shoulder l5 below the contact portion I4, two spaced movable conductor elements I,

5 each of which comprises a flat electric current conductor bent approximately midway of its length to form a U-shaped blade member having va substantially flat rectangular bight 2 and legs 3. For actuating the blade members I, I

4 provide a close-coupled insulating finger-operable block handle 4 of suitable insulating material which has specially formed cooperating channels or grooves in each face thereof extendin throughout the length of the block. Thus the handle has on its inner face a longitudinal groove 5 of a generally rectangular shape for registering nested engagement with the rectangular bights 2 of the blade members so as to reinforce and increase the rigidity of the fiat rectangular bights as well as prevent movement thereof relatively to the handle and also to insure parallel alignment of the blade members in a multipole switch. The close-coupled block handle 4 may be of any suitable insulating material such as wood, molded compound and the like made up longitudinal finger receiving and insulating depression or channel 6, the sides of which are corrugated at I, and the sides of the strips are provided with longitudinal thumb grooves 8 which are also corrugated as shown. For clamping the rectangular bights 2 of the blade members in the registering rectangular groove of the handle 4, suitable means such as screws 9 are provided.

For pivotally supporting the U-shaped blade members I, each is provided with a hinge stud III which terminates in a flattened contact portion II that is of materially less the stud to provide parallel contact surfaces inwardly offset from opposite sides of said stud and provided with an axial opening for the reception of a hinge bolt I2. Also cooperating with each of the blade members I is a terminal or contact stud I3 which terminates in a cylindrical contact portion I4 and which has below the contact portion a motion limiting shoulder I5 for stopping the movement of the blade member in the switch closed position. alignment with more uniform contact pressure, the studs I0 and cylindrical contact surfaces. portion I4 of the stud I3 may right circular cylinder, I have found less deterioration of the contact surfaces from arcing if the contact portion is in the form of an elliptical cylinder with the portions of lesser curvature presented to the legs 3 of the blade I, as shown in Fig. 2. For the required contact area and mechanical rigidity at the hinge end, the thickness of the flat portion II of the hinge stud is materially less than the thickness of the contact portion It of the contact stud. The spacing of the legs 3 of the U-shaped blade member I is sufficiently less than the thickness of the cylindrical contact portion I4 to insure firm high pressure line contact between the legs 3 and the contact portion. In order to guide the legs 3 for the spreading action required during contact closure, the contact portion I4 is suitably shaped as by rounding the tip, shown more clearly in Fig. 2.

While the contact take the form of a Since the thickness of the fiat contact portion I I of the hinge stud In is materially less than the For obtaining good contact I3 are provided with suitable thickness than N spacing of the legs 3 of the U-shaped member, the

ends I6 thereof are inwardly offset to a spacing substantially equal to the thickness of the fiat contact portion. For the desired contact action between the blades 3 and the flat contact portion, suitable resilient washers I1 are provided on the bolt I2. Thus with a given weight of conductive material, both the current conducting and heat dissipating capacities thereof can be utilized most effectively since the required mechanical strength is provided by the rectangular bight of the relatively light U-shaped blade I spanning the round pivot stud ID with a flattened end and the cylindrical contact stud I3 so that relatively high currents can be conducted without serious overheating. The relatively wide spacing of the legs 3 at the bight with the inward offset only at the pivot ends thereof facilitates circulation of the air therebetween to dissipate heat.

In order to insure more firm contact between the blades 3 and the contact portion I4 of the contact stud I3, especially under shock conditions, the blades 3 may be resiliently interconreception of a raised able insulating material, movement of the stud through the opening being limited by a shoulder 22 below which are deformed lugs 23 for preventing rotation of the stud relatively to the base when a clamping nut 24 and washer 25 are tightened to the holding position.

In order that switches embodying my invention may be used with fuses having blade type terminals, the stud I0 is illustrated as a combination fuse clip and switch stud. all as disclosed and claimed in my copending application for Letters Patent of the United States, Serial No. 597,884, filed June 6, 1945, which subsequently issued as Patent 2,458,511, on January 11, 1949. Thus there is provided a clip member 26 for holding the bladev type terminal 21 of a fuse 28 in relatively high pressure substantial line-contact against the cylindrical surface of the stud Ill. The clip member 26 is resilient and of relatively low electric current conductivity in comparison with the conductivity of the stud I0. The clip member 26 is provided with a relatively small contact surface 26 opposed to the surface of the stud I 0 for engaging the fuse terminal 2'! in relatively high pressure contact having a minimum of area and approximating point-contact. For easy insertion of the fuse terminal 21, the contact surface 26' is convex and is so positioned as to localize the pressure approximately midway of the line of contact between the surface of the stud and the fuse terminal.

For mounting the stud I 0 and the clip member 26 on the base 2|, the clip member is secured against a shoulder 29 of the stud by a shouldered plug 30 which is threaded into the bottom of the stud, as shown in Figs. 1 and 3, and the stud I0 and the clip member 26 are interlocked to prevent relative movement by providing the shoulder 29 of the stud III with a depressed surface for the portion 3| on the clip member. The free end of the plug 30 projects into a hole in the base 2I and as shown is threaded for a fastening screw 32 under the head of which are a lock washer 33 and a bearing washer 34. For mounting the other end of the fuse, I provide a fuse clip 35 which is essentially similar in construction to the combination fuse clip and stud I0 except that the cylindrical portion does not include a flat surface for hinging the switch blade. Also, the clip 35 is provided with a threaded portion 38 which projects through an opening in the base 2| and is held in position on the base by a nut 31 over a washer 38. The stud 36 is thus suitable for terminal connections.

When a double-throw switch is desired, two contact studs I3 are provided respectively positioned on opposite sides of the hinge stud III as will be obvious to those skilled in the art. If a double-throw switch is to be used for individually controlling two different. circuits, each of which is to be fused separately, then as shown in Fig. 5 the contact stud I3 for each throw is provided with a fuse clip member 26 for receiving the tongue type terminal 21 of a fuse 28 between the cylindrical surface of the stud and the contact surface 26 of the clip.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modificajacent the bight, a block tions that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A multipole finger-operable knife switch having in combination, a row of round contact studs, an opposite row of round hinge studs, each terminating in a fiat portion having a U-shaped blade member pivotally mounted thereon and comprising a flat conductor bent approximately midway of its length to form a substantially flat rectangular bight for sustaining high contact pressure upon engagement of a corresponding round contact stud between the legs thereof adhandle of insulating material having a finger receiving and insulating channel in one face thereof extending throughout the length of the handle and a parallel rectangular groove in the opposite face thereof for registering nested engagement with the rectangular bights of the U-shaped blade members with the legs thereof extending transverse the groove, and means for clamping the bights of the U- shaped blade members in said groove to maintain the blades in a row and in longitudinal aligmnent with the channel in the handle.

2. A multipole finger-operable knife switch having in combination, a first row of round hinge studs, each terminating in a relatively thin flat portion normal to the row, an opposite row of round contact studs, each terminating in a rounded contact portion having its axis in opposing alignment with the flat portion of the corresponding .stud in the first row and provided with a motion-limiting shoulder below the contact portion, a movable row of blades, each comprising a flat conductor bent approximately midway of its length to form a U-shaped blade member having a substantially flat rectangular bight for susgroove taining high contact pressure upon engaging the rounded contact surface of a corresponding stud between the legs thereof adjacent the bight up to the limit of the shoulder and the ends of said legs being inwardly offset for straddling engagement with the relatively thin fiat portion of the corresponding stud in the first row, means for pivotally clamping the offset ends of each blade to the flat portion straddled thereby to maintain the blade in pivotal conducting relation therewith, a block handle of insulating material having a finger receiving and insulating longitudinal channel in one face thereof extending throughout the length of the block and a parallel rectangular in the opposite face thereof for registering nested engagement with the rectangular bights of said U-shaped members with the legs thereof transverse the groove, and means for clamping the bight of each U-shaped blade member in said groove to maintain the blades in fixed alignment with the channel in the handle during pivotal movement of the row of blades.

WINTON G. HARLOW.

REFERENCES CITED I The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 605,067 Badeau June 7, 1898 979,050 Ward Dec. 20, 1910 2,200,509 Lindae May 14, 1940 2,313,771 Rossman Mar. 16, 1943 FOREIGN PATENTS I Number I Country Date 352,756 Italy Sept. 21, 1937 

